To some extent, however, there is a demand in the market for plastics material containers which do not have a circular cross-section but a cross-section diverging from this, such as for example an oval basic shape. In addition, a multiplicity of methods are known from the prior art for producing plastics material containers of this type. In this way, it is known for example for specific areas of the outer wall of the plastics material pre-forms to be heated more intensely so that they stretch to a greater degree during the subsequent stretch blow moulding procedure, so that a bottle shape diverging from a circular cross-section is formed as a whole.
This procedure is also referred to as “preferential heating” in the prior art.
A blow moulding apparatus is known from JP 08174552 A.
In this case thermally insulating reinforcing materials are used, so that the shape as a whole has a double structure. In addition, heating devices and water perforations for cooling water are provided. A possibility of controlling a thickness in a peripheral direction of a bottle is likewise described in JP 63207630 A. In this case an elliptical blow mould is likewise provided here.
The apparatus and a method of producing non-cylindrical articles from pre-forms of PET are known from U.S. Pat. No. 4,380,526. In this case blow moulds are used which themselves have an elliptical cross-section. The surface of the blow mould against which the thermoplastic material is forced can have effects upon the shaping. To this end it is proposed to apply a thermally insulating material in the region which forms the container. In this case this Teflon material is intended to improve the coefficient of friction with the plastics material of the plastics material pre-form and to reduce the transmission of heat from the material of the pre-form to the blow mould.
In the German Patent Application DE 10 2009 021 792.4—not yet published—of the Applicants a method has been described in which the plastics material pre-forms are touched in part by means of a contact element and are tempered in this way. The contents of the disclosure of this application are hereby also made the subject matter of the present application by reference in its entirety.